Fluid compressor



June 214, 1938. B. s. AIKMAN Y 2,121,534

FLUID COMPRESSOR Filed July 2, 1936 3 Sheets-Sheet 1 l INVENTOR BURTO N EIK MAN #i ATTORNEY June 21, 1938. B. s. MKMAN FLUID COMPRESSOR Filed July 2, 1936 5 Sheets-Sheet 2 INVENTOR BURTON E AIK MAN E* Wwf/M ATTORNEY `June 21, 1938, l B. s. AIKMAN FLUID COMPRESSOR Fi1ed Ju1y 2, 1936 5 Sheets-Sheet 3f @www y INVENTOR BURTON SAIKMAN A. mmm,

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Y B ATTORNEY Patented June 21, 1,938

Burton S. Aikman, .Wilkinsburgg The Westinghouse Air Brake a corporation of Pennsylvania merding, Pa.,

Pa., assignor to Company, Wil- Application July z, 193s, serial No. 88,497

. 5 Claims.

This*Y invention relates to compressors, ,and more particularly to an improved uid compressor'and control means therefor.

y In order to secure high volumetric eiiiclency in the operation of a compressor, it is desirable that the duid to be compressed be completely discharged irom the -compressionchamber upon each compression stroke of the piston, without 'leakage of said uid to other parts of the compressor or to the atmosphere.

One object of lmy invention is to provid'e a compressorihaving these advantages, which object is accomplished by'employing a compressor piston adapted to operate through a b ody of liquid contained in the compression chamber, the resulting displacement of the liquid being effective to compress the air or other fluid, while ensuring the complete discharge of said fluid from the compression chamber.

Another object of my inventionv is to provide a compressor of the above type having means for utilizing the uid compressing liquid or water as a cooling medium for rapidly dissipating the heat of compression of said fluid.

It is desirable that the compressor be operated` to deliver a supply of fluid under pressure free from oily vapors, which are apt to develop due to leakage of lubricant past the compressor piston into the fluid other causes.

It is a further object of my invention to provide a compressor having water displacement means for compressing air or other fluid, in which the possibility of undesired vaporization o1' lubricant from the compressor into said air or 'iluid is obviated.-

Another object of my invention is to'provide a compressor embodying means for automatically varying the clearance volume within the iluid compression chamber for effecting any desired degree ci loading of the compressor.

Another object is. to provide power-circuit'controlling means operative to eiect initial unload- `ing of the compressor prior to cutting off the power supply of the compressor driving motor.

A still further object` of the invention is to provide an improved uid compressor having automatic load controlling means associated therewith.

Other objects and advantages will appear in the following more detailed descriptionl of the inventiomttaken with reference to the accom- Dilnying drawings, in which: Fig. i is a diagrammatic, vertical view, mainly in section, of a iluid compressor equipmentA .compression chamber, or for embodying my invention; Fig. 2 is a diagrammatic, vertical view, partly in section, of a compressor equipment embodying another form of my invention; Fig. 3 is a sectional view taken on the line 3 3 of Fig.2; Fig. 4 is a sectional view taken on the line 44 of Fig. 2; Fig. 5 is a vertical, sectional view of a portion of a compressor embodying another form of my invention; Fig. 6 lis a sectional view taken on the line 6 6 of Fig. 5; and Fig. '7 is a fragmentary, sectional view illustrating an alternative construction for the compressor shown in Fig. 5. l

Referring to Fig. 1 of the drawings, there is provided a fluid compressor designated generally at I0, a reservoir Il for receiving fluid compressed by the compressor, a liquid supply valve ldevice I2, and an unloading valve device I3.

The compressor I0 comprises a' crank case I5 having a crank case chamber I6 and vertical cylinder bores I l and I8,l and cylinder casing sections I9 and 20, which are mounted on said crank case in alignment with' the bores I1 and I8, re-

spectively. An elongated, hollow piston 22v is slidably mounted in the bore I I and extends through an intermediate chamber 23 formed in the crank case and into a compression chamber 2 within the cylinder casing I9. The chamber 24, which preferably is of larger diameter and has a substantially greater volume than that displaced by the piston 22, is adapted to contain a body of liquid, such as water, hereinafter referred to as the compressing liquid.

A ilexible packinggasket 26preferably made of rubber and having an inclined iange`21, is interposed between the crank case I5 and the cylinder casing I 9, the ilange on said packing gasket having sealing engagement with the wall of the piston 22 for preventing escape of liquid nsl or fluid under pressure from the compression chamber 24. A downwardly sloping collar 28 is secured to the piston 22 within the chamber 23 for defiecting possible leakage iiow of liquid past the packing gasket 2li into an annular channel 29, which is formed in the lower wall of said chamber and has an open drainage port 30.

Fittedlwithin the piston 22 vand secured thereto by anysuitable means, suchas by a rivet 32, is a journal member 33 carrying a wrist pin 34,- to which is pivotally connected the upper end of a connecting lrod 35, the lowerend of said connecting rod being journaled. on a crank shaft 36. which is rotatablyA mounted in the crank case I5 and which may be driven by any suitable means (not shown). 1

Slidably mounted' in the borel I8. is a hollow ed on the cylinder casing flange portion 50 mounted on the cylinder cas' ing 20. l Disposed in a chamber 5 formed in the upper portion of the cylinder casing I9 is a discharge valve 52, which is urged toward a seat 53 by a spring 54` interposed between said valve and the iiange portion 49. The valve 52 is adapted to control communication Vbetween the 'compression chamber 2'4 and the manifold pipe 48. In like manner a chamber 55 is formed in the upper portion of the cylinder casing 20 and contains a discharge valve 56, which is urged into engagement with a seat 51 by a spring 58. The valve 56 is adapted to control communication between the. compression chamber 4| and the manliold pipe 48.

It will be noted that the compression chambers 24 and upper walls of the 4| are so formed as to provide substantially conical surfaces 59 and 60, respectively, which slope upwardly toward the respective valve seats 53 and 51 so that there are no pockets or cavities in which air or other fluid to be compressed may lodge.' y

The cylinder casings I9 and 20 are.provided with aligned valve portions 10 and 1|, respectively, and an intake member 12 is clamped between said valve portions so as to form a chamber 13 in the valve portion 10 and a chamber 14A in the valve portion 1|. These chambers communicate with a central passageway 15 which is connected through a passage 16 to an air intake strainer 11 of any desired type, and is also connected through a restricted passage 18 to a liquid supply pipe 19.

An inlet valve 8| is provided for controlling communication from the passageway 15 through the chamber 13 and apertures 82 in the cylinder casing I9 to the compression chamber 24. Similarly, aninlet valve 84 is disposed in the cham-e ber 14 for controlling communication from'the passageway 15 to the compression chamber v4| by way of said chamber and apertures 85 in the cylinder casing 20. Springs 81 and 88 are provided for urging the respective valves 8| and 84 to their seated positions. 1

The supply valver device I2 isvprovided for controlling the supply of compressing liquid to the compression chambers 24 and 4| of the compressor, and may comprise a casing section 90 having a chamber 9| connected to a supply of liquid (not shown) under a predetermined pres- -sure head through a pipe and-passage 92. A

manually adjustable valve of any desired type', such as the rotary plug valve 98, may be interposed in the passage 92 for regulating the rate of supply of liquid to the chamber 9|. A casing section 93 is mounted on the casing section 90, and a iiexible diaphragm 94 is clamped between the casing sections 90 and 93, so as to form at one side thereof a chamber 95"and at the other side a chamber 96. The chamber 96 is connected to the supply pipe 19 and is separated from the chamber 9|- by an apertured wall 91.

Disposed in the chamber 9| of the valve device upper end I2 is a valve 99,l having a stem |00 which extends through the aperture in the wall 91 and is secured to the diaphragm 94, said valve` being adapted normally to engage a seat formed on said wall for cutting oft communication between the chambers 9| and 96. The diaphragm 94 is adaptedto be subjected to uid pressure for controlling operation of the valve 99, fluid under pressure being supplied from the compression chamber 4| of thecompressor by way of a port formed in the wall of the cylinder casing 20, past a .non-return check valve |02, which is disposed in a valve chamber |04 in said casing, and through a pipe |03 to the chamber 95.

For cooling the iluid under pressure and any accompanying compressing liquidrsupplied Afrom the compressor through the manifold pipe 48, there is provided a cooling pipe |05, which is concates byvvvayl of a branch pipe |06 with the reservoir II.

In addition, the pipe communicates with a chamber |01 in an automatic drain valve device |08, which chamber is connected through a conduit |09 with t e lowermost portion of the reservoir II. Disposed in the chamber |01 is a normally seated valve I|| operably connected to a lever ||2, which is fulcrumed on a pin ||3 carried by a lug formed within the casing. A iioat ||4 is mounted on the lever ||.2 and is adapted to effect the opening and closing of said valve according to the level of liquid in the chamber |01 for controlling communication from said chamberto a drain pipe H5..

In order to provide for ing of the compressor in accordance with the iiuidpressure built up in the reservoir II, unloading means is provided which is automatically operative in response to a ervoir pressure for reducing the amount of compressing liquid con,tained in the compression chambers 24 and 4|, thereby 4automatically varying the volumetric e'mciency of the compressor.

Referring to Fig. 1 of the drawings, the unloading vaive device I3 comprises a hollowcasing |,1 within which is mounted a vertical sleeve member IIB, having a bore formed in vertical alignment with a substantially conical valve seat |20, which is formed in the lower portion of said casing adjacent a discharge opening I2I.

Clamped between a cover plate |22 and the of the casing ||1 of the unloading valve device I3 is a flexible diaphragm |23, which has at its upper side a chamber |24 connected the automatic unloadby way of a pipe |25 with the reservoir and which has at the other side a spring chamber |26. A follower member |21 engages the lower side of the diaphragm |23 and is slidably mounted in the vertical bore within the sleeve m'ember I I8,

the lower end of said member having screwthreaded connection with the stem |28 of a valve `element |29, which is formed substantially com- --communicating by way of a pipe |35 and a similar passage (not shown) in the cylinder casing 20 with the compression chamber 4|.- A spring v |36 is disposed in the chamber |26 of the unloading valvedevice between the head |31 of the predetermined resthe valve element 29 follower member I 21 and the sleeve member ||8 for urging the diaphragm |23, the follower, and

element normally engages the seat |29.

In the following description of the operationl of the compressor equipment, it is assumed that the manually operated valve 98 has been ad-l justed to permit ow of liquid at the desired rate from the liquid supply through the pipe vand passage 92 to the chamber 9| of the liquid supply valve device- I2, while the compression chambers 24 and 4| of the compressor I2, which are adapted to contain liquid, arev initially empty. Since the uid pressure in the reservoir I'| is initially low, the spring |36 in the unloading valve device I3 maintains the valve |29 in seated position.

When the crank shaft 36 is rotated, the pistons 22 and 49 are reciprocated in the usual manner through the medium of the respective connecting rods 35 and 42. During the initial compression strokes of the piston 49, sufiicient fluid pressure is built up in the compression chamber 4| to unseat the check valve |92 and force fluid under pressure through the pipe |93 to the chamber 95 of the liquid supply valve device I2. lFluid under presi sure thus supplied to the chamber 95 moves the diaphragm 94 the valve 99. in a position The plug valve 98 having been set 'to supply liquid at the desired rate of iiow through the passage 92 to the chamber 9|, liquid is then free to-iiow from said chamber and past the unseated valve 99V to the chamber 96.

Upon each'suction stroke' of the piston 49, a partial ,vacuum is createdv in the compression chamber 4|, s o that air or other iluidis drawn into said chamber by way of the strainer 11, the

passage 16, and through the valve chamber 14 and passages 95. At the same time, a quantity of liquid is also drawn from the chamber ,96 of the supply valve device |2 through the pipe 19 -pistons 22 and and restricted passage 18 to the passageway 16. and thence by way of the other communications just mentioned into the compression chamber 4|.

Similarly, upon the suction stroke of the pis-` ton 22, air or other fluidl is drawn through the strainer 11, passage 16, passageway' 16, past the unseated inlet valve 8| and' through the valve chamber 13 and passages 82 4into-the compression chamber 24, while liquid is drawn into said chamber by way of the restricted passage v19 and through said other communications.

As compressing liquid is thus supplied to the compression chambers 4I and 24, liquid ows through the pipes I 33 and.|35 to the seat of the reservoir and theV fluid compressed in thechamber 4I unseating the discharge valve 66 and flowing by way of-the same communications to the reservoir I|. Y

After ashort period of operation, compressing liquid will have been supplied in the manner just described to the compression chambers 24 and 4I in quantities such that, when displacedby the '49, respectively, at the upper limits of the respective strokes thereof, the compressing liquid entirely fills vthe compression upwardly, so that the valve downwardly and thereby unseatsv II 2 so Adischarged from the reservoir II nected chamber |91 past the unseated valve I|| further compression chambers, with the result that complete exp sion of the iluid under pressure from said chambers to the manifold'48 iseiected during the successive compression strokes of the pistons..

When the compressor |9 is thus operating, at its full volumetric elciency, since a quantity of compressing liquid is drawn from the supply vinto .tact with' the air or fluid being compressed, is-

thus enabled to absorb heat therefrom, and as portions of the liquid are forced from the compression chambers into thermal contact with the discharge valves, the latter are thereby constantly cooled during operation of the compressor.

It will be apparent that the compressing liquid is in this way utilized as ameans for absorbing and carrying on from the compressor the heat of compression of the air or other uid, the hotA liquid, together -with the air or fluid under pressure, being cooled while flowing from the manifold 48 through the cooling pipe |95. As the fluid under pressure ows from the pipe |96 through the pipe I 96 into the reservoir II, most' oi the liquid ls separated therefrom and ows downwardly from the pipe |95 into the chamber |91 of the automatic drain valve device I 98.

. while liquid condensed in the reservoir collects in the lowermost portion thereof, whichis connected with said chamberv through the pipe |99.

If the level of `liquid in the chamber I||1 and in the reservoir I| rises above a predetermined point, the iioat I|4 is adapted to operate the lever as 4to open the valve III. Liquid is then and the conand through the pipe IIE.

When the pressure of the iiuid in the reservoir has beenv built up to a predetermined value. fluid under pressure supplied therefrom to the chamber |24 of. the unloading valve deviceA I3 and acting on the diaphragm |23 overcomes the force of the spring |36, and moves the diaphragm, the follower |21, and the valve |29 downwardly,A thereby moving the valve |29 out of sealing engagement with the seat |29. compressing liquid is then quickly discharged from the compression chamber 24 of the compressor |9 by way ofthe passage |34, pipe |33, port .|3I and the discharge opening |2I, and also from the compression chamber 4| by way of the pipe |35, port |32, and

said discharge opening.

As a result of this discharge of compressing liquid from the compression chambers of the compressor, a clearancevolume is created in each of said chambers at the end of the compression stroke of the respective piston therein, so that the compressorls thereby unloaded. Operation of the compressor may be continued,4 although the pressure of air or other duid thereafter compressed in said chambers will be insumcient to cause the unseating of the discharge valves 62 and 66 against the forces of the springs 64 and 66, respectively.

. 1 When the pressure of air or `other iluid in the reservoir is reduced by under pressurec therefrom for any desired purpose, the uid pressure in the chamber |24 of the unloading valve device Il is correspondingly re-- withdrawal oi!` fluid which is similar to shown in Fig. 1, and hereinbefore described, comdiaphragm |23, follower |21 and. valve |29 up' wardly so as to seat the valve. With the valve |29 closed, continued operation of the compressor is then effective to cause the compression chambers to be again filled with compressing liquid in the manner hereinbefore described, so that the compressor is rendered operative to compress air or other uid.

Referring to Fig. 2 of the drawings, in which is illustrated a modified form of my invention, there is provided a compressor |40 of the twocylinder type, a driving motor |4| for operating the compressor by means of suitable gearing (not shown), a liquid supply valve device |42, a liquid reservoir |43, areservoir |44 for receiving fluid under pressure, and an automatic unloading control device |45.

The compressor |40, the operative principle of that of the compressor prises a crank case |41 having a crank case chamber |41a and provided with vertical portions |48 and |49, on which are mounted cylinder casings |58 and |5l, respectively.

A piston |52 is slidably mounted in a bore formed in an interior sleeve portion |53 of the crank'case' within the vertical portion |49,` the piston having an enlarged head( |54 and a skirt portion |55, which is adapted to overhang the sleeve portion |53 and to project into a chamber |58 surrounding said sleeve portion. The piston |52 is adapted to be operated through the medium of a connecting rod |51, which is connected to a wrist pin |58' carried by said piston, while the connecting rod may be journaled on the usual crank shaft (not shown), the head |54 oi said piston being arranged to reciprocate in a compression chamber inder casing and is of substantially larger diameter than said head. The compression chamber |59 is adapted to 'contain a quantity of compressing liquid, as hereinafter described.

Oil for lubricating the Apiston and bearing surfaces may be supplied by any desired means (not shown) For collecting lubricating oil wiped from the piston |52, an annular groove |5| is formed in the upper rim of the sleeve portion |53 adjavapor lfm.

cent the piston bore therein, said groove being connected through a passage |52 with a cham- Y ber |53 formed in the crank case |41. The chamber |53 is adapted to communicate with the crank case chamber |41a by way of a bore |55, valve' chamber |65 and apertures |61 formed in a valve cage |68 which has screw-threaded connection with the interior wall of the crank case. A ball check valve |59 is preferably disposed in the valve chamber |66 for preventing back iiow of air or from the crank case chamber, said valve being urged to its seat by a spring |10.

Clamped between the vertical portion |49 oi the crank case and the cylinder casing |5| is an annular packing ga -ket |13, Awhich has an upwardly inclined iiange |14 adapted to maintain sealing engagement with the skirt is preferably interposed between the vertical portion |49 and the packing gasket |13 for resisting the downward thrusts to which the gasket may-be subjected due to the force exerted by the liquid under pressure in the chamber |59.

A drain passage |15 is connected to the lowermost portion of the chamber |55 for carrying ofi any liquid which might seep past the packing gasket |13, the drain passage being of a restricted 'travel of the piston head |59, which is formed in the cyll portion |55 of' 4the piston |52. An annular supporting member size so as to permit suicient build up of uid pressure in the chamber |55 upon each downward stroke of the piston |52 vto force oil collected in the depression |5| through the passage |52, chamber -|63 and bore |55 and thence past the check valve |59 to the crank case chamber |41a.

rIn order to promote effective cooling of the air or other iiuid compressed in the compression chamber |59, a cooling grid |80 is mounted in the upper portion of the chamber beyond the limit of |54, the top of the grid being adapted to fit within the substantially conical upper wall of the cylinder casing |5|. The cooling grid |80 may be constructed in any suitable form to provide a large surface area, and, as is best shown in Fig. 4 of the drawings, the grid may comprise a vertically arranged sheet or plate of substantially spiral form, the outer por tionv of the grid being secured to the cylinder casing |5| by any suitable means, such as by welding.

Disposed in a valve chamber |8| formed in the upper portion'oi the cylinder casing |5| is a discharge valve |82, which 'is adapted to engage a seat |83 for controlling communication between the compression chamber |59 and the valve chamber. The discharge valve |82 4has a'hollow stem- |84 slidably mounted in a suitable bore in the adjacent end of an exhaust manifold pipe |85,

which is mounted on the cylinder casings |50 and ISI. A spring |86 is interposed between the valve stem |84 and a wall of the manifold pipe |85 for urging the discharge valve |82 to its seated position. 'I'he valve chamber |8| communicates by'way of the manifold pipe |85 and a pipe |81 with the reservoir |44. In actual practice the reservoir |44 may preferably be located on a lower level than the manifold |85 and pipe |81, so as to ensure proper'iiow thereto of liquid discharged from the compressor.

A clearance control valve device |88 is provided for automatically regulating the amount of oompression liquid maintained in the compression chamber |59. 'Ihe clearance control valve device comprises a casing, which may be formed integral with the cylinder casing |5|, and which has a valve chamber |90 connected through an aperture |9| with the lowermost portion of the compression chamber |59. Disposed in the valve chamber |90 is a valve |92 which is adapted tp be normally held seated by a spring |93 interposed between said valve and the wall of the chamber. The valve |92 has a fluted stern |95 mounted to slide in a suitable bore in the casing, which bore connects the valve chamber' |90 through a chamber |96 to a liquid discharge pipe |91.

A cover |99 is mounted on the clearance control valve casing, and a exible diaphragm 200 is between said cover and the casing, forming a pressure chamber which is connected by way. of'a passage and pipe 202 with a control pipe 203. The diaphragm 200 is adapted to operate the valve |92 through the medium of a follower element 204, which is interposed between said diaphragm and the stem |95 within chamber |95.

It is not deemed necessary to show and describe in detail -the internal construction and arrangement of the parts of the other compressor cylinder included within the vertical casing portio'n |48 and cylinder 'casing |50, as it will be understood that this cylinder is substantially the same as that comprising the vertical portion |49 and cylinder casing |5| hereinbefore described.

Associated with the cylinder casings |50 and |5| is an intake manifold 205, which communiiluid and cates with the atmosphere, or the source of tobe compressed, by` way of a filter 201,

which is adapted to conduct compressing liquid' supplied through a pipe 208 by the liquid supply valve device |42 to the respective compression chamber within the cylinder casings |50 and as will be hereinafter described.

Each of the cylinder casings |50 and |5| of the compressor is provided with an inlet valve means for controlling communication between the intake manifold 206 and each of the compression chambers. For the purpose of illustration, the inlet Valve casing |50 said means is shown in Fig. 3 of the drawings, comprising a valve 2|0 which is disposed in a valve chamber 2 connected with the the valvechamber 2|@ isa normally open valve v terposed in said 2123, which has a stem 224 secured to the diaphragm 2|1 by means of a nut 225 or other suitable means, and which is adapted 'to engage a seat 226 for cutting oif communication between the chambers 220 and 2|8.

, The liquid reservoir |63 is located above the level of the compressor |40so as to provide thel desired liquid pressure head, and is adapted to be supplied with liquid by way of a pipe 226, leading from a suitable source of liquidunot shown, a manually adjustable valve 229 being inliquid. The reservoir |43 is equipped with a float valve 230, which is contained in an apertured cage 23| mounted within the reservoir, the float valve being adapted `to engage a seat 232v to cut oli' communication from the reservoir to atmosphere when the liquid reaches a predetermined level. 'I'he reservoir |43 is preferably adapted to contain sumcient liquid to ll the compression chambers of the compressor after saidrcompressor yhas been completely unloaded.

The unloading control device |45 is designed to the compressor |48 to the reservoir |06 ilrst to efect the rapid unloading of the compressor, so

that thecurrent drawn by the driving motor hilt,l

will be thereby reduced, and then to cut off the supply of current to said motor. -Means is also included in the unloading control. device i635 for automatically effecting the unloading ci the compressor when the supply of current tothe driving motor 94| is cut ofi for any reason. As shown in the drawings, the unloading control device |85 comprises a pressure responsive control valve 235 for automatically varying the quantity oi compressing liquid held in the compression chambers oi the compressor M0, and a pressure controlled switch device 23? associated with said casing for con trolling the supply o .current delivered to the driving motor Il.

The control valve 236 is slidably mounted in a chamber 238 communicating through a passage 203e with the pipe 203, and is adapted to engage a. seat 233 for controlling communication between munication past the means associated with theV cylinder through a chamber 220 and pipeA pipe for regulating the ilow of v predetermined maxi-v -llquid. The piston casing 235 containing anuidi.'

'communication between said the chamber 238 and a chamber 238a, which is connected by way of a passage and pipe 239 with the reservoir |44. 'Ihe valve 236 is of the snap action type, the area thereof which is normally within the seat 233 and exposed to the chamber 239e being less than the total pressure area of l the valve when unseated. 'Ihe valve vided with grooves 236a formed therein adjacent the wall of the. chamber 238 for permitting comvalve within said cli'amber, which is normally open to the atmosphere through a passage 234. 'I'he valve 236 is adapted to engage a seat 240 which is of larger diameter than the seat 233 and is formed on the outer wall of the chamber 238, for closing the atmospheric passage when the valve is operated to establish communication between chambers 239a and 238.

For urging the valve 236 toward seated position a spring 24| is provided, one end of'which 'has a hook formed thereon that is adapted to contact 260 adapted to bridge stationary contacts 23| and 262 for controlling a power circuit through which current is supplied for operatingthe driving motor |4I, whichfcircuitincludes a conductor 263 leading to a suitable power generatin'g means (not shown), the switch contacts 262, 260 and 26|, a conductor 264, the motor |4|, and a conductor265, which-in turn isconnected to said generating means. 'I'he stationary contacts 23E and 262 are mounted on an insulator tion of the casing 235, as shown in the'drawings. i For operating the movable contact 260 of the switch device 231" there is provided a vpair of pistons 235 and 246, which are slidably mounted in a central bore formed inthel casing ,236 and whichare joined by an integral'stem 247. The piston '226 has a stem 249 which extends upwardly through an opening in a sleeve portion 250 of the casing. The movable contact 260 is .secured to, but insulated from, the upper .end oi the stem' 249; A spring 253 isinterposed between the p|ston 205 and the upper wall of the sleeve portion 250 for normally maintaining the movable contactin engagement with the stationary contacts 26H and 232.

passage ttwith thepassage 203a, said chamber being adapted to containa body of oil or other 245 i@ provided with aperl tures. 256i communicating with the chamber. 256 which is formed at the lower side of said piston, apertures and the chamber 245i being controlled by alight plate ele-l ment'ttt., which is loosely iltted on the stem 28W and is adapted to` overlap the apertures 254. The plate element 250 vis adapted to permit free new ci liquid from. the chamber 256m the'chambei' 25@ by way of the apertures 258 in the piston.

236 is promember 267, which is carried by the upper por- 255, and has extending therethrough a restricted port 258 which is adapted to register with one ofthe apertures 256 for permitting only a limited ow of liquid in the opposite direction. suitable means (not shown) may be employed for preventing undesired turning of the plate element 256 relative to the stem 241.

A vertical groove 259 of substantial flow capacity is formed in the inner wall of the casing 235 for establishing communication between the chambers 255 and 25| upon a partial movement of the piston 245 toward its uppermost position. It will be apparent that, upon full upward movement of the connected pistons 245 and 246, stem 249, and contact element 260,- an annular bead 246a of the piston 246 will ing engagement with a gasket 251 secured within the central bore of the casing 235, while the movable contact 260 will be moved out of engagement with'the contacts 26| and 262.

Means is provided for actuating' the control valve 236 to cause unloading of the compressor |40 when the supply of' power to the motor |4| is cut off for any reason, said means including a rod 210 which is slidably mounted in a suitable bore in the lug 248 and is arranged to engage the lower end of the lever 242 for relieving the valve 236 of the pressure of the spring 24| and thereby permitting the valve to be forced from its seated position vby a relatively light fluid pressure'acting in the chamber 23911. A spring 21| is interposed between the lug 248 and a collar 212 on the end of the rod 210 adjacent the lever 242 for urging said rod toward said lever, the power of the spring 21| being greater4 than that of the spring 24|.

v The other end of the-rod 210 is pivotally connected by means of a pin 213 to the lower portion of an armature`214, which is journaled intermediate its ends on a pin 215 carried by a lug 216 formed on a magnetic core element 211, said element being mounted on the casing 235. DisposedA around the core element 21,1 is a magnet coil 219, which is connected by means of conductors 28| and 282 to the respective conductors 263 and 265 intermediate the power source and the switch device 231, said coil being adapted when energized to exert sufficient magnetic pull on the armature 214 to cause the upper portion thereof to engage the core element 211, thereby 'maintaining the rod 210 out of engagement with the lever 242 against the force of the spring 21|, as shown in the drawings. The rod 210 is provided with a stop collar 283 adapted to engage the lug 248 for limiting movement of said rod toward the left-hand by the spring 21|, and for thereby preventing movement of the armature 214 beyond the magnetic field of the coil 219.

It is assumed that, before the compressor |40 is operated, both compression chambers thereof are empty and the reservoir |44 is at atmospheric pressure, lwhile the chamber 2|8 of the supply valve device |42 is open to the atmosphere through the pipe 203, passage 203er, chamber 238 and passage 234, so that the valve 223 of that device isunseated. In order to condition the compressor for operation, the valve 229 is opened to permit the supply of compressing liquid ut-the desired rate of flow through the pipe 228. the liquid vthe chamber 220 in the liquid supply valve device |42, past the vopen valve 223, and through the pipe 208 to the intake manifold 206. The iiow of liquid into the reservoir continues until the float valve 230 is raised into engagement with the seat 232.

When it is desired to start the compressor, the

circuit is closed for supplying current to the motor Y |4| by way of the conductor 263, switch contacts be brought into seal- Vtion to that already Any 262,260 and 26|, conductor 264, the motor, and the return conductor 265, thereby operating said motor to reciprocate the pistons of the compressor |40 in the usual manner. The supply of current through the motor circuit also energizes the magnet coil 219, and the armature 214 is then pulled into engagement with the core element 211.v

On this movement of the armature 214 the rod 210 is moved against the spring 21 thereby compressing this spring and relieving the lever 242 of the force of this spring, so that the spring 24| moves the lever 242. This movement of the lever 242 is transmitted through the stem 243 to move the valve 236 into engagement with the seat 233 so as to cut oi communication between the reservoir |44 and the passage 203m, and to connect the chamber 20| of the clearance control device |88, and the chamber 2|9 of the liquid supply valve device |42 to the atmosphere.

As illustrative of the operation of both pistons of the compressor |40, it is evident that as the piston |52 moves downwardly in the suction stroke, compressing liquid is drawn into the compression chamber |59 from the manifold 206, said chamber being rapidly charged with compressing liquid supplied from the liquid reservoir v|43 as-already described. Thereafter, upon each suction stroke of the piston |52, air or other fluid toA be compressed is drawn through the iilter 201 and the manifold 206, and past the inlet valve the cooling grid |80, while the of compression liquid to said ber |59 containing continued supply chamber is also effected at a rate determined by the .setting of the valve 229.

It will be understood that, when piston |52 is at its lowermost position, substantially the full surface area of the grid is exposed to the air or gas in the compression chamber |59. As the piston |52 moves in its compression stroke to displace the body of liquid contained in the compression chamber to compress the air or gas therein, the heat of compression of this gas is at' least partially absorbed by the grid |80 by reason of its large surface area, and the grid then transfers the heat to the compressing liquid as it rises into thermal contact therewith. Since the quantity of liquid supplied to the compression chamber during the previous suction stroke, in addiin this chamber, is more than enough to fill the chamber when the piston |52 completes its compression stroke, the top and hottest portion of the body of liquid is thereby expelled past the discharge valve |82, together with the air or other fluid under pressure, as the piston approaches its uppermost position. The liquid and iiuid under pressure then now by way of the manifold and pipe |81 to the reservoir |44, and the liquid may thereafter be disposed of by one of the methods disclosed in the other embodiments of my invention.

When the pressure of fluid supplied to the resl ervoir |44 has been built up to the desired maximum, asdetermined by the setting of the spring 24| of the unloading control device |45, the uid under pressure supplied by way of the pipe and passage 239 to the chamber 2390. shifts the valve 236 away from the seat 233 andinto engagement with the seat 240. Fluid under pressure is then supplied from the chamber 23911 through the chamber 238 tothe passage 203a, and thence by way of the pipe 203 and pipe and passage 202 to the chamber- 20| in the clearance control valve device |88, thereby moving the diaphragm 20|,

follower element 204 and stem |96 so as to unseat the valve |92. With the valve |92 unseated.

compressing liquid is drained from the compression chamber |59 of the compressor by way of the aperture i 9| valve chamber |90, past said valve and through the chamber |96 and drain pipe |91, thereby effecting unloading of said compressor in the manner already described, it being understood that this operation is at the same time performed in both cylinders of the compressor.

Fluid under pressure supplied to the pipe 203 as just described also ows to the chamber 2|6 in the liquid supply valve device |42 and moves the diaphragm 2|1, stem 224 and valve 223 upwardly until the valve engages the ting oiT further supply of compressing liquid to the compression chambers of the compressor.

Meanwhile fluid under pressure supplied from the passage M by way of passage .252 to the chamber in the unloading control device |45 acts upwardly against the piston 246, and also acts on the surface of the oil or other liquid so as to force slow iiow thereof from the chamber 25| through the restricted port 256 of the element 256 and the adjacent passage 254 in the piston 245 to the chamber 255 therebelow. The connected pistons 246 and 245 are thereby gradually shifted upwardly together with the stem 259 and the movable contact 260, it being noted that this initial upward movement of the elements of the switch mechanism does not serve to disengage the movable switch contact 260 from the stationary contacts 26| and 262, which are of such length established around groove 259 in the wall of the casing 225, whereupon further flow of the oil from the chamber 25| to the chamberV 255 is permitted at a fast rate, and uid pressure in the chamber 25| is enabled to shift the pistons 266 and 225, stem 249 and movable contact 262 upwardly with a snap-like action, thereby quickly disengaging the movable contact from the stationary contacts 26| dnd 262 so as to cut oil` further supply of current to the driving motor Mi. The compressor having already been substantially unloaded, the

current taken by the driving motor |29 is reduced to a minimum, so that the final operation of the switch. device 231 to interrupt the current supply circuit is thus accomplished `'with minimum arcing at the switch terminals.

It will be understood that while the valve 222 of the supply valve device |22 is seated. liquid continues to ow by way of the valve 226 and pipe 220 to the reservoir |53 until the float valve '230 is seated. the reservoir being then substanif thepressure of fluid in the reservoir is -now caused to fall below the pressure required to maintain the valve l253e in engagement with the seat 240 in theunloading control device |456, the spring 24| becomes effective to operate the lever 2li2'so as to move the valve 222 into engagement with the seat 233,`the valve at the same time seat 226, thereby cutmoving away from the seat 240 for opening communication from the chamber 238 through the passage 234 to the atmosphere; Fluid under pressure is then vented from the chamber 25| by way of the passages 252 and 203e, chamber 2 39 and passage 234, so as to permit the spring 259 to force downwardly the piston 246. stem 249 and movable contact 260, together with the stem 241 and piston 245, the plate element 256 being shifted on the stem 241 away from the piston 245 to permit rapid ow of oil from the chamber -255 through the passages 254 to thev chamber 25|. The movable contact 260 is thus operated to bridge the stationary contacts 26| and 262, so that current is again supplied to the motor |4| for operating the compressor |40.

At the same time, fluid under pressure is vented from the chamber 20| of the clearance control valve device |88 by way of the passage and pipe 202, pipe 203, passage 20311, chamber 236 and atmospheric passage 234, so that the spring |9315 enabled to seat the valve |92 for cutting oi further communication between the compression chamber |59 and the drain pipe |91. Fluid under pressure is also vented by way of the communications already mentioned from the chamber 2|9 of the liquid supply valve device |42, permitting the valve 223 to be-unseated by the pressure of liquid acting thereon within the seat rib 226. Compressing liquid is thensupplied from the reservoir |43 to the compression chambers of the compressor |40 in the manner hereinbefore described, so that said compressor will again be loaded.

If the power circuit through the conductors 203.

and 265 is interrupted, so'as to cut off the supply of current to both` the motor |4| and to the magnet coil 219 on the unloading controlk device |45, the armature 214 is relieved of magnetic pull toward the core element 211 and the spring 21| then shifts the rod 210 to the left. Upon engagement of the rod 210 with the lower end of the lever 262, the further expansion of the spring 2li overcomes the opposing force of the lighter spring 24|, and moves the lever 252 away from the stem 243 permitting the valve 236 to be moved from the seat 233 by the fluid under pressure in the chamber 239e and in the connected reservoir |46.

With the valve 236 thus opened, the compressor |20 will be unloaded in the manner hereinbefore described. It will thus be seen that the unloading control device is adapted to function, when the compressor is stopped for any reason, automatically to effect unloading of the compressor. so that the compressor will always be initially un-l leadedv when it is desired to resume operation thereof.

Another form of my invention-is ,disclosed in Figf of the drawings, in which is shown a compressor comprising apiston casing section 200, a liquid displacing piston 30| operatively mounted therein, and an enlarged'cylinder casing section 202 mounted on said piston casing and havinga compression chamber 302. In this embodiment of the invention there is associated with the compressor meansv for collecting compressing liquid discharged from the compression chamber, coolof the piston 30| the chamber being adapted to contain'a body of compression liquid of considerably greater volume than that displaced by said piston, so that the extent and the speed of the al ternate rise and fall of the liquid -in said chamber caused by reciprocation of the piston will be relatively less than the length of stroke and speed of the piston. It will be apparent that undesired surging of the compressing liquid inthe compression chamber 303 is thereby minimized, so that a.relatively high piston speed'may be permitted Without causing undue pounding of the compressing liquid againstthe walls of the casing section 302.

A horizontally disposed baiile 309 comprising a plate having a plurality of holes thereinis mounted within the compression chamber 303 above the upper limit of travel of the piston 30|, said baiiiebeing adapted to check surging of the compressing liquid at the surface thereof, so as to ensure that the surface of the liquid will be maintained substantially even for preventing undesired mixture thereof with the air to be cornpressed during operation of the compressor. Mounted between the baiile 309 and the upper wall of the compression chamber 303 is a cooling grid 3'|0, which in the embodiment of my invention being described comprises a hollow central core 3H provided with radially extending, vertically arranged plate portions 3|2, as .best shown in Fig. 6 of the drawings. The function of the cooling grid 3|0 is similar to'that of the cooling Agrid |80 shown in Fig. 2 of the drawings and al ready explained. y

.A flexible packing gasket 3|4 and an annular supporting member SI are interposed between the piston casing section'300 and the cylinder casing section 302, the inner portion of said gasket being in sealing engagement with the piston 30| for substantially preventing leakage of compressing liquid from the chamber 303.

It will be noted that the piston 30| has a substantially conical top portion 316, so that the piston upon its compression stroke 4tends to force the displaced liquid laterally and outwardly within the compression chamber 303. If desired, the piston 30| may be adapted to reciprocate within a cylindrical hood 3I8, as shown in Fig. '7 of the drawings, for further ensuring displacement in lateral directions. of the compressing liquid upon the upward strokes of said piston, the hood being mounted within the cylinder casing section 302 and having a plurality of vertically extending apertures such as the slots 3|9 formed in the wall of the hood for permitting free passage of the liquid to and from the compression chamber 303.

An inlet valve 3 20 is provided for controlling communication between an intake chamber 32| and the compression chamber 303-, this valve being urged toward its seated position by a spring 322. The intake chamber 32| communicates with a passage 323 leading from an air filter 324. 4

'Mounted in a valve chamber 326 above the cooling grid 3|0 is a discharge valve 321, which is urged toward seated position by a spring 328 and is adapted to control communication from the compression chamber by way of 4said chamber 326gwith a chamber 329 formed in a cap 330, which is carried by the `cylinder casing section 302. The chamber 329 communicates with the reservoir 306 by way of a pipe 342.

The liquid supply reservoir/ 308 has a chamber 332 open to the atmosphere by way of an opening 333 in the upper wall thereof. A tube 334 having Ving downwardly into the valve 340 closed,

A and 2 of the drawings.

a restricted passage 335 is mounted within the reservoir 308, the open end of said tube extendchamber 332, and the other end thereof being connected byway of a pipe 334:1. with the intake chamber 32| of the compressor. Contained in the chamber 332 is a iioat 336 having a stem 336a which is pivotally mounted on a pin 331 carried by a lug 338 formed within the reservoir 308. The free end of the stem 336a is pivotally connected to the upper endl of-a pin valve,340, which is adapted to control communication from the chamber 332 tothe cooling pipe 301. i v

The cooling pipe 301 may be of any suitable form for providing the desired cooling surface,

and may have associated therewith a fan 34| for effecting circulation trap 305 and the pipe of air over the pipe.I The 305a, are adapted always to contain a quantity of liquid sufficient to prevent flow of air or other fluid under pressure from the reservoir 306 through-said trap to the cooling pipe 301. yThe trap 305 is connected by way of a pipe 343 with a pipe 342, which communicates at one end with the reservoir 306, and at the other end with the chamber 329 in the cap 330 above the discharge valve of the compressor.

Assuming that the necessary quantity of compressing liquid has been initially supplied to the compression chamber 303 of the compressor, and that the reservoir 308 also initially contains suilicient liquid to causelthe float 336 to maintain the the principle of operation of the piston 30| to effect the substantially isothermal compression of air or other iiuid in the compression chamber 303 is similar to that of the hereinbefore described operation of the other embodiments of my invention as shown in Figs. 1

In operation, upon the compression strokes of the piston 30 I, fluid under pressure together with a quantity of compressing liquid is forced past the discharge valve 321, and through the chambers 326 and 329 to the pipe 342. Fluid under pressure thence passes into the reservoir 306, while most of the liquid is permitted to iiow downwardly through the pipe 343 into the trap 305. Liquid deposited in the reservoir 306 by condensation or in any other manner is also free to flow into the trap 305 through the pipe 305a.

Upon the suction strokes of the piston 30|, liquid is drawn from the reservoir 308 through the restricted passage in intake chamber 32| and past the open inlet valve 320 to the compression chamber 303 in the compressor, while'the air or other fluid to be compressed is also drawn into saidv chamber by way of the filter 324, passage 323, intake chamber 32| and past said inlet valve. I

When 4the level of the liquid contained in the reservoir 308 has been lowered sufficiently by withdrawal of liquid therefrom just described, the about the pin 331 so as to lift the pin valve 340 from its seat. `With the pin valve 340 unseated, the pressure of uid'in the reservoir 306, and in the pipes 342 and 34| connected thereto, forces liquid from the trap in the manner oat 336 tilts the stein 336a.

305 and pipe 305a upwardly, through the cooling pipe 301 and past the valve' the tube '334,'pipe 334a, the

a sumcient quantity oi liquid to prevent escape of fluid under pressure' from the reservoir 306 through the trap to the pipe Iill.V

The liquid in `circulating through the pipe 301 is cooled with the aid oi' the fan 34| so as to `ensure that the liquid supplied to the reservoir 3 will be at a 'low temperature and thus ready l i'or further use in the compressor.

Means is thus provided for supplying compressing liquid to the compressor atvthe desired rate, separating the liquid discharged from said com'- pressor, and for then cooling the liquid thus.

separated and rendering it available for further use in thevcompressor. From the foregoing it will be apparent that my invention comprises an improved compressor operative to eiect thesubstantially'isothermal compression of air or other fluid by mechanical displacement of a body of liquid, which liquidis4 also utilized as a cooling medium for dissipating the heat of compression, the compressor having meam associated therewith for automatically controlling the compressor in accordance with the pressure of iiuidy supplied thereby, and for unloading the compressor prior to cutting of! the supply of power to the driving motor therefor, so that the compressor may always be unloaded before starting. v

While several illustrative embodiments of the invention have been described in detail, it is notv vmy intention to limit its scope to these embodiments or otherwisethan by the terms of the appended claims.

Having now described my invention, ,what I claim as new and desire to secure by Letters Patent, is: A

1.-. In a geous' iluid compressor, in combination, awiiuid compressing piston for compressing -iluidin a compression chamber, me'ans operative upon running the compressor for supplying liquid to the compression. chamber at a restricted rate, said chamber having a liquid discharge communication. and means operated upon a predetermined increase in the pressure of iluid compressed by the compressorior opening said communication for permitting the, discharge of the liquid Supplied to slid chamber.

2. In combination, a reservoir. a compressor ber mmmmpmynmaunderprmwma sion chamber communicating with said reservoir and adapted to contain a body of liquid, anda liquid displacing piston operable to reciprocate in said compression chamber for compressing fluid above said body of liquid, Aand means responsive to the pressure oi iiuid in said reservoir for varying the amount of liquid contained in the compression chamber and consequently the loading of the compressor.

3. In combination, a compressor having a compression chamber adapted to contain a certain quantity of liquid and a piston operative in said chamber for compressing gaseous fluid above said liquid, means-for draining said chamber. a reservoir adapted to contain substantially the same quantity of liquid, means for supplying liquid thereto at arestricted rate, and means operative upon starting the compressor for establishing communication from said reservoir to said chamb'er, whereby said chamber is initially iilled at a fast rate, and is further supplied with liquid at a restricted rate.

4. In combination, a gaseous iiuid compressor comprising a compression chamber adapted to contain a quantity oi liquidand a liquid displacing piston operable to reciprocate in said compression chamber for compressing gaseous uid above said liquid, means for supplying liquid to the compression chamber while the compressor is running, and means responsive to a predetermined pressure of uid compressed by the compressor for cutting oii the supply of liquid to said compression chamber and for draining liquid therefrom for unloading ythe compressor.

5. In* combination, a gaseous iiuid compressor comprising a compression-chamber adapted to contain a quantity of liquid and a liquid displacthe compression chamber while the compressor is running, and unloading metering spring and valve opposing pressures of said spring and o f iluid compressed by the compressor lfor controlling the ot liquid from Asaid compression -cham- BURTON' S. AMAN.

means comprising a means subject to the 

